Summary

The peripheral leukocyte migration inhibition assay has been adapted as an in vitro assay of cell-mediated immunity to a soluble antigen extract of nasopharyngeal carcinoma (NPC) and as an assay for transfer factor (TF) activity in this system. Ten normal individuals with positive Epstein-Barr virus (EBV) antibody titers (1:16 or greater) demonstrated leukocyte migration inhibition (mean ± S.E.) of 36.8 ± 3.4%, at an NPC antigen concentration of 50 µg/ml, compared to a mean migration inhibition of 13.8 ± 5.3% in 10 EBV-negative normal subjects (EBV antibody titer, < 1:4), and this difference was statistically significant (p < 0.002). Four NPC patients in remission demonstrated a mean migration inhibition of 28.8 ± 4.0% when their leukocytes were incubated in the presence of NPC antigen while 4 patients in relapse did not demonstrate migration inhibition (mean 4.3 ± 5.0%), and this difference was significant (p < 0.03). TF derived from EBV-positive donor leukocytes converted leukocytes of EBV-negative normal recipients to reactivity against the NPC antigen in 7 of 9 cases, and this response was highly significant (p < 0.002). The ability of TF to convey reactivity was specific and correlated with EBV humoral immunity in the TF donor. TF also conferred similar reactivity upon the leukocytes of 2 of 4 NPC patients in relapse.

Footnotes

↵1 This work was supported by a grant from the National Cancer Institute of Canada.